1. Field of the Invention
The invention concerns a labeling device, and more particularly, a device for applying adhesive to an entire label while preventing the label from sticking to the paste drum.
2. Description of the Prior Art
FIG. 4 illustrates a conventional labeling device.
This device consists of a label suction drum (a) which utilizes an interruptable negative pressure for first holding and later releasing individual labels (f), a paste drum (b) and adjustably positioned adjacent to the aforementioned label suction drum (a) for applying an adhesive paste to each successive label (f), a label dispenser (c) adjustably positioned adjacent to drum (a), and a rotatable container transfer drum (e) for supporting containers (d) and bringing the containers into contact with individual labels held by the label suction drum for facilitating attachment of the labels (f) to the containers (d).
This type of labeling device makes it difficult to completely coat the individual labels with adhesive, as solidly coated labels are very likely to become attached to the paste drum (b) instead of remaining on the label suction drum (a) for transfer to the containers (d).
This phenomena is due to the fact that the negative pressure exerted on the labels by the suction drum (a) is weaker than the adhesive strength of the glue.
In an attempt to remedy the above-discussed problem, it has been known to insert a comb-like metal piece between the paste drum (b) and the labels (f) carried by the rotatable transfer device, to peel labels from the paste drum (b) and replace them on the label suction drum (a). With this type of device, parallel grooves (g) from recessed bands on the circumference of the drum (b) prohibit glue from being applied to that part of the label coinciding with the grooves, as illustrated in FIG. 5.
In other words, the labels (f) are coated horizontally with multiple stripes of glue. The teeth of the comb-like device push against the uncoated parts of the labels so that labels are released from the paste drum (b) and transferred to the label suction drum (a).
Generally, this type of device is adequate. However, in the following it may prove deficient:
1. In the case of containers likely to be used in damp places, i.e., shampoos and detergents, the uncoated stripes absorb moisture and swell, creating a poor appearance and reducing the value of the goods.
2. In the case of smooth-surfaced containers, such as plastic, hot-melt type strong adhesives are needed. Strong adhesives such as hot-melt type are beginning to predominate the field. However, these strong adhesives make separation of labels from the paste drum difficult, especially in high speed labeling operations.